Electric discharge tube comprising a liquid cathode and a capacitative ignition electrode provided therein



Jane 32, N. WARMOLTZ 2,495,831

ELECTRIC DISCHARGE TUBE COMPRISING A LIQUID CATHODE AND A CAPACITATIVE IGNITION ELECTRODE PROVIDED THEREIN Filed Aug 10, 1948 NICOLA/LS WARM 0LT Z.

11v VEN TOR.

BY 2 1; Qua /k AGENT.

Patented Jan. 31, 1950 UNITED STATES PATENT OFFICE! Nicolaas Warmoltz, Eindhoven, Netherlands, as-

signor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application August 10, 1948, Serial No. 43,368 In the Netherlands September 11, 1947 3 Claims.

This invention relates to an electric discharge tube comprising a liquid cathode in which a capacitative ignition electrode is provided, the discharge path in this tube being surrounded by a screen which extends a little above the cathode surface.

Somewhat analogous constructions are known for tubes without capacitative ignition electrodes.

Discharge tubes comprising a capacitative ignition electrode may be used with advantage for high frequencies since, in contradistinction to a resistance ignition electrode, little energy is required for igniting a discharge by means of a capacitative ignition electrode. In addition reignition does not occur at higher frequencies at the capacitative ignition electrode, as does occur in resistance ignition electrodes.

However, a tube having liquid electrodes still exhibits the disadvantage that with a rapidly returning positive voltage re-ignition readily occurs at a liquid cathode. If the anode is liquid, back-fire easily occurs in the negative phase. This is why the use at high frequencies still involves difliculties.

The present invention has for its object the mitigation of these disadvantages. According to the invention, in an electric discharge tube having an envelope composed at least in part of insulating material and comprising a liquid cathode in which a capacitative ignition electrode is provided, and in which tube the discharge path is surrounded by a screen which extends close above the cathode surface, this screen separates the discharge space completely from the cathode space and further extends horizontally above the cathode surface, the width of the screen, between the discharge path and the wall, preferably being at least 5 times as great as the spacing of the screen from the cathode surface. Both the screen surrounding the discharge path and the horizontal extension above the cathode surface may be constituted by the wall of the tube. By the construction according to the invention it is achieved that little ionization occurs at the limit between the cathode surface and the wall, and we have found that in this manner re-ignitions, which occur substantially at the wall, are considerably reduced. If the anode also is liquid it is particularly advantageous to construct the anode space in the same manner. Tubes according to the invention do not exhibit back-fires or re-ignitions even at frequencies of 10,000 cycles/sec, with voltages exceeding 4 kilovolts and currents of the order of magnitude of amps. It is possible to raise the frequency to more than 100,000 cycles/sec. with not excessively high currents.

Instead of capacitative ignitors: use may also be made of other ignition electrodes: which are not subject to re-ignition. If the ignition electrode is subject to re-ignitiorr solely the anode should be constructed in the aforesaid manner.

In order that the invention may be more clearly understood and readily carried into effect it will now be described more fully with reference to the accompanying drawing, given by way of example, in which Fig. 1 represents a discharge tube of glass in which the screen surrounding the discharge path extends above both the oathode and the anode surface, and Fig. 2 represents a different construction of the cathode surface in which the tube wall extends horizontally and very close above the cathode surface. In Fig. 1 the reference numeral l denotes the insulating wall of the discharge tube, and the numerals 2 and 3 designate the insulating wall of the cathode space and anode space respectively. The cathode consists of a quantity of mercury 4 comprising a supply conductor 5. The anode is designated by 6 and the supply conductor by 1. In the cathode a capacitative ignition-electrode is provided which consists of a piece of wire 8 on to which a layer of glass 9 is sealed. The insulating wall of the tube 1 merges into the horizontal insulating screen In above the cathode surface and into a screen H above the anode surface. In Fig. 2 component parts corresponding to those of Fig. 1 bear the same reference numerals. Since in the present case the cathode space has such a height that the insulating wall 2 extends very close above the cathode surface no additional screen is necessary.

What I claim is:

1. A vapor discharge tube comprising an evacuated envelope having a cathode chamber and an anode chamber, each of which chambers are provided with wall portions, an ionizable liquid electrode having a capacitative ignition electrode in the said cathode chamber, a screen member interconnecting said cathode chamber and said anode chamber and thereby providing an enclosed path for the said vapor discharge, the said screen member having a flanged portion extending substantially horizontally in the said chamber containing the said ionizable liquid electrode and spaced from the said electrode, the width of the said flanged portion between the path of the said vapor discharge and the wall portion of the said chamber being approximately five times the dis- 3 tance between the said flanged portion and the said liquid electrode.

2. A vapor discharge tube cOmprising an evacuated envelope having a cathode chamber and an anode chamber, each of which chambers are provided with wall portions, an ionizable liquid electrode having a capacitative ignition electrode in said cathode chamber, a second ionizable liquid electrode in said anode chamber, a screen member interconnecting said cathode chamber and said anode chamber and thereby providing an enclosed path for the said vapor discharge, the said screen member having a flanged portion at each extremity thereof, each of which flanged portions extends substantially horizontally in one of the said chambers containing a said ionizable liquid electrode and which is spaced from the said liquid electrode, the width of the said flanged portion between the path of the said vapor discharge and the wall portion of the said chamber containing the said flanged portion being approximately five times the distance between the said flanged portion and the said liquid electrode of the chamber containing the said flanged portion.

3. A vapor discharge tube comprising an evacuated envelope having a cathode chamber and an anode chamber, each of which chambers are provided with wall portions, a liquid electrode in said anode chamber, a screen member interconnecting said cathode chamber and said anode chamber and thereby providing an enclosed path for the said vapor discharge, the said screen member having a flanged portion extending substantially horizontally in the said anode chamber containing the said liquid electrode and spaced from the said electrode, the width of the said flanged portion between the path of the said vapor discharge and the wall portion of the said anode chamber being approximately five times the distance between the said flanged portion and the said liquid electrode.

NICOLAAS WARMOLTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,210,674 Knowles Aug. 6, 1940 2,428,000 Winograd Sept. 23, 1947 2,444,204 Mulder June 29, 1948 

